drm: Account property blob allocations to memcg

[ Upstream commit 26b4309 ]

DRM_IOCTL_MODE_CREATEPROPBLOB allows userspace to allocate arbitrary-sized
property blobs backed by kernel memory.

Currently, the blob data allocation is not accounted to the allocating
process's memory cgroup, allowing unprivileged users to trigger unbounded
kernel memory consumption and potentially cause system-wide OOM.

Mark the property blob data allocation with GFP_KERNEL_ACCOUNT so that the memory
is properly charged to the caller's memcg. This ensures existing cgroup
memory limits apply and prevents uncontrolled kernel memory growth without
introducing additional policy or per-file limits.

Signed-off-by: Xiao Kan <814091656@qq.com>
Signed-off-by: Xiao Kan <xiao.kan@samsung.com>
Link: https://patch.msgid.link/tencent_D12AA2DEDE6F359E1AF59405242FB7A5FD05@qq.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: kanxiao

drivers/gpu/drm/drm_property.c

@@ -561,7 +561,7 @@ drm_property_create_blob(struct drm_device *dev, size_t length,
 	if (!length || length > INT_MAX - sizeof(struct drm_property_blob))
 		return ERR_PTR(-EINVAL);
 
-	blob = kvzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);
+	blob = kvzalloc(sizeof(struct drm_property_blob) + length, GFP_KERNEL_ACCOUNT);
 	if (!blob)
 		return ERR_PTR(-ENOMEM);